#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <string>

#define ll long long

using namespace std;

int main()
{
	int n, a, b;
	cin >> n >> a >> b;

	int ans = 0;
	if (n > max(a, b))
	{
		int x = min(a, b);
		int y = n - x;
		while (x >= 0 && y <= b)
		{
			++ans, --x, ++y;
		}
	}
	else
	{
		int x = 0;
		int y = n;
		while (x <= a && y >= 0)
		{
			++ans, ++x, --y;
		}
	}

	cout << ans;
}